Passengers flying out of the George Bush Intercontinental Airport in Houston, Texas airport during the next three months will have an opportunity to make their travels a little bit more ‘green.’ Continental Airlines and the U.S. Transportation Security Administration are piloting a program that lets travelers use their cell phones or PDAs in lieu of a paper boarding pass.

Houston Chroniclereported Tuesday that the system involves displaying encrypted bar codes on mobile device screens. The information displayed onscreen is then scanned by airport officials at boarding checkpoints.

If everything goes well with the pilot program, mobile device-based boarding passes could eventually do away with the need for paper documents entirely—with the exception of photo ID. Continental, Houston Chronicle reported, is the first U.S. airline to test out the technology.

Of course, Continental and the TSA are not just trying out this new system out of a moral obligation to reduce paper use. Instead, the program is designed to heighten airport security, in particular to (hopefully) eliminate ticket fraud. In the past, people sometimes succeeded in using fraudulent paper boarding passes to get past checkpoints. The TSA is confident that the new tech can’t be cracked.

TSA is also looking at expanding the use of encrypted bar codes for tickets, both on paper and on screens, Houston Chronicle reported. Data encrypted in the pilot program includes passenger name and flight details.

The TSA has another reason for going with encrypted digital flight info: regulation by the International Air Transport Association (IATA), which has mandated that all airlines stop using magnetic strip technology on boarding passes by the end of 2008. Houston Chronicle said in its report that IATA also is requiring airlines to start using two-dimensional bar codes (which look like a rectangle of TV ‘snow’ rather than parallel lines) by 2010.